640020647 has 8 divisors (see below), whose sum is σ = 738993696. Its totient is φ = 542932992.

The previous prime is 640020611. The next prime is 640020659. The reversal of 640020647 is 746020046.

640020647 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 640020647 - 2¹⁰ = 640019623 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640020677) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 470618 + ... + 471975.

It is an arithmetic number, because the mean of its divisors is an integer number (92374212).

Almost surely, 2^640020647 is an apocalyptic number.

640020647 is a deficient number, since it is larger than the sum of its proper divisors (98973049).

640020647 is an equidigital number, since it uses as much as digits as its factorization.

640020647 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 942697.

The product of its (nonzero) digits is 8064, while the sum is 29.

The square root of 640020647 is about 25298.6293502237. The cubic root of 640020647 is about 861.7831431242.

The spelling of 640020647 in words is "six hundred forty million, twenty thousand, six hundred forty-seven".